The goal of this K23 award is to provide the training and research experience necessary for me to become a leading researcher in the development of technology-based resources that improve the quality of mental health (MH) services. I propose to receive advanced training in the following areas: (1) mHealth intervention development and evaluation; (2) biomedical informatics; (3) implementation science; (4) clinical trial design, implementation, and evaluation; (5) grant writing and project management; and (6) ethics and the responsible conduct of research within these domains. My mentorship team includes senior level investigators with active federally-funded research projects, extensive experience mentoring early-career investigators, and expertise in the following areas: iterative design, development, and evaluation of technology-based MH interventions (Ruggiero), biomedical informatics (Lenert), implementation science (Nemeth), clinical trial design and evaluation (Ramakrishnan), mechanisms underlying evidence-based treatments (Kazantzis), and development of evidence-based treatments for youth and families (Deblinger). I will apply the skills learned in my training to a research project where I will develop and conduct a feasibility RCT of PRACTICE, an app I designed using patient and provider input (NIMH F32) and aimed at increasing provider use of and patient adherence to homework (HW) during youth MH treatment. HW is assigned by providers in-session and completed by patients between sessions to enable therapeutic skills and behaviors to generalize to ?real-world? settings. HW is integral to evidence-based treatment, but use and adherence generally are low due to several barriers, many of which are addressable via mHealth resources. Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) is used as a treatment model for this work to ensure translatability to a wide range of MH treatments. PRACTICE will be developed and usability testing will be conducted with providers and patients to guide refinements. A feasibility trial will be conducted with 20 providers and 60 treatment-seeking youth and their caregivers, recruited from local community-based clinics and randomly assigned to TF-CBT enhanced with PRACTICE vs. standard TF-CBT. Outcomes (PTSD, depression, disruptive behavior) will be assessed at baseline and 3- and 6-months post-baseline, and targets (HW use and adherence) will be assessed via coded audio recordings of treatment sessions and weekly check-ins with patients. Post-trial qualitative interviews will assess reactions to the app and identify barriers and facilitators relating to use. In preparation for the next phase of this research, a large-scale hybrid effectiveness-implementation trial of PRACTICE (NIMH R01), strategies for implementation will be assessed via qualitative interviews with community-clinic providers, supervisors, and senior leaders, and quarterly advisory meetings with the directors of 5 community-based service agencies. This research complements my training and career trajectory, and will provide valuable data toward understanding how mHealth can positively affect HW use, adherence, and ultimately, the quality of MH services.